Fixes #1308. Make UriData tests case-insensitive

Author: sgrekhov

LibTest/core/Uri/Uri.dataFromBytes_A01_t02.dart

@@ -33,7 +33,7 @@ check(List<int> data, String mType) {
   Uri uri = new Uri.dataFromBytes(data, mimeType: mType);
 
   Expect.equals(base64.encode(data), uri.data?.contentText);
-  Expect.equals(mType, uri.data?.mimeType);
+  Expect.equals(mType.toLowerCase(), uri.data?.mimeType);
 
   Expect.equals("data", uri.scheme);
   Expect.equals("", uri.userInfo);

LibTest/core/UriData/UriData.fromBytes_A01_t02.dart

@@ -23,7 +23,7 @@ check(List<int> bytes, String mType) {
   UriData uriData = new UriData.fromBytes(bytes, mimeType: mType);
 
   Expect.equals(base64.encode(bytes), uriData.contentText);
-  Expect.equals(mType, uriData.mimeType);
+  Expect.equals(mType.toLowerCase(), uriData.mimeType);
 }
 
 main() {